Powdered material press and control



J1 B. CUTLER APOWDERED MATERIAL PRESS AND CONTEUL Filed Jan. 2, 1941 zsheets-sheet i www / fil @y gig 1 nTToE/VEY Jan.*4, 1944. .1. B. cuTLERPOWDERED MATERIL PRESS AND CONTROL Filed Jan'. 2, 1941 2 Sheets-Sheet 2INVENTOR vLJQHN B. CUTLE:

ATTORNEY I Patented Jan. 4, .1944,

UNi'rEo vs'r.%\rr='.s PATENT;

OFFICE- POWDERED. MATERIAL PRESS AND CONTROL John B. Cutler. HaddonHeights, N. I., assigner 4 A to The Baldwin Locomotive Works, acorporation of Pennsylvania i' Application January z, 1941,'sma1 No.312.782

11 claims. (c1. 1li-1s) This invention relates generally tol pressesforforming products from powdered material and particularly to means forcontrolling both the density and size of pieces produced.

Products of powdered material are formed by lling a mold cavity withnely powdered metal or other material and then compressing the powder toa cohesive state by a plunger. Ma-

v following description of the accompanying. drawings in which:

Fig. 1 is a vertical section through a hydraulic v press embodying aportion of my improved apchines for this general purpose are very oldbut they have not been capable of producing products under largepressures withinprecision limits as to dimensions and/or density. Theproblem of providing a. machine capable vof 'sucht precision operationbecomes especially dimcultwhen Ait is attempted to have the pressproduce the articles rapidly and particularly when the articles requireexceptionally large compressive forming forces. My invention isparticularly applicable to` powdered metals although other kinds andforms of loose materials maybe used and also in the preferred specificembodiment of the invention I employ a hydraulic press although certainfeatures of my invention are applicable to mechanical presses as well.

It is an object of my invention to provide improved means for formingproducts .from loose material with a high degree of dimensionalaccuracy. It is also an object to provide improved means for controllingthedensity of the products, especially while maintaining the desireddimensional accuracy of the products.

A furtherv objectis to provide; an improved .press and control therefor`whereby precision operation is capable ofbeing obtained` under largecompressive forces which with my improved apparatus may be upwards of200,000 or 300,000 pounds. 1

[i further object is to provide improved means for accomplishing densityand/or dimensional control automatically during operation of theequipment.

paratus;

Fig. 2 is a combined wiring and mechanical f stationary crossheadt. 'Asis` usual in hydraulic presses a main cylinder t., formed in crosshead At, supports a lling tank t from which oilor other suitable liquid underlow pressure ows through a filling valve l, of well-known form andoperates, to cylinder E during downward movement of a main ram t. Ifdesired, a pair of additional rams and cylinders generally indicated atQand l0 may beJ employed, all of the. rams being 'suitablyconnected toan upper movv able platen Il which is guided by the side columns 2 and3. A lower movable platen l2 is y also guided by side columns 2 and 3and ispmoved downwardly by a -ram and cylinder generally indicated ati3, .the cylinder being formed inv lower crosshead l. The ram isconnected by a lower movable crosshead i4 to side rods I5 and iii whichare connected to the piston I2; The platen l2 4is normally biasedupwardly by one- -or more small constant pressure pushback Vrams andcylinders such as generally indicated .at l1.

A still further object is to provide a hydraulically operated press with.improved means for controlling the press operation so as to obtain thedesired dimensional ,control over the products.

A further object is to provide an improvedl apparatus that is economicalin operation and maintenance and is durable and rugged combined with apositive and yet sensitive operation so as toproduce products having Aavery substantial degree of uniform accuracy as to density anddimensions.

Other objects and advantages `will be more apparent those skilled in theart from the The press .structure so far described is of well-1 knownoonstruction and hence further detailed description is not necessary.

To form a powdered product a diemold gen erally indicated at 20 islpositioned within a suitable recess in platen l2. This mold isspeciically shown las having aninner annular wall 2| which specificallyforms the mold cavity while an outer relatively thick annular band v22is shrunk on to the die moldV 20. This operation causes the die 20 to bepreloaded un- -der compression stress, thus preventing or minimizingexpansion of. the die under load vand vthereby' maintaining a highdegree of radial die Y mension of the product. The foregoing novelpreshrunk die structure isV held in positionby a .sizeal'ld sizes. Thisoperation, however.

The die shape may be such that it has a smooth periphery so as to formbushings or the like or it may have, gear teeth to form gears, etc. Theplunger 24 is supported upon stationary crosshead I and has a verticalslot 25 through which a crosshead 26 extends for connection to platen I2by rods 21 and 28. If the products such as 'I bushings, gears or thelike require a coaxial hole a pin 29 may be removably threadedly securedto crosshead 26 and extend upwardly through stationary plunger 24 intodie 2i. A movable compressing plunger 30, carried by upper platen Il,has the same conformation' as die 2l and also has a suitably ventedcentral bore 3l to receive core pin 29.

To form a product, powdered metal or other material is poured inanyusualmanner into the mold cavity around the core pin 29 and excesspowder is swept oi! by a usual well-known sweeper arm on the usual-feedbox. The powder remaining in the mold will be level with the topthereof. Platen II is then moved downwardly under hydraulic pressure toforce plunger 35 into themold cavity. When the product is fullycompressed the platen II is raised by supplying hydraulie pressure tothe cylinderspace 33 beneath differential piston 8. 'I'he product isejected by supplying rluid pressure to cylinder I3 thereby movingplatenI2 and its mold 25 downwardly over the product which rests on stationaryplunger 24. It will be understood that during the compression stroke theincreasing compressing pressure on the powdered metal causes thefrlctional contact between the powdered metal and the mold wall toincrease and this friction causes platen I2 to yield downwardly againstthe constant pressure pushback plungers and cylinders I1. This yieldingof the platen I2 4under the foregoing friction load effects what isknown as a floating mold action. This allows the frictional resistanceto be less than if the mold re mains stationary. In my present inventionI provide improved means adapted to variably cooperate with the floatingaction so as' to dimensionally control the products while at the sametime obtaining complete freedom of operation of the oating action andalso obtaining uniform density of products even though accompanied bythe variable dimensional control.

. The foregoing cooperative relation is of such a character that I amable to employ therewith improved means for initiating and controllingthe actuation of the dimensional control mechanism in response to thedimensions of products ejected from the press.

In many instances in the past it has' been proposed to control thedimensions of a product by employing presses having only a fixed strokefor the compressing plunger and then ,adjusting the depth of the moldwhereby more powdered material could beadded to increase the axialdimension of the product. However, this involved disadvantages amongwhich is that suc-A been accompanied by a variable density of thesuccessive products because the density iinally obtained was dependentupon the volume of powdered metal and the xed strokeof the compressingplunger. In my improved arrangement the plunger 30 is adaptedto have avariable stroke controlled solely by AtheI density of the individualarticles thereby allowing the density of the product to be substantiallyindependent of the quantity of powdered metal within the mold. Byutilizing this characteristic I am able to freely adjust the mold platento obtain dimensional control without sacrifice of density control.

To obtain densication control I preferably employ means responsive tothe actuating force applied to the plunger 30 specifically bydetermining the hydraulic pressure in cylinder 5. When this pressurereaches a predetermined value the supply of'hydraulic pressure isdiscontinued and the plunger 30 is returned upwardly. Hence, the plungerwill continue downwardly until the main cylinder pressure reaches apredetermined densifying value, the stroke therefore not being of flxedlength. One form of mechanism capable of accomplishing the foregoingdensifying control is diagrammatically indicated in Fig. 1 wherein apostive displacement piston pump 35 of the reversible Hele-Shaw type isconnected in a usual manner by pipes 36 to the cylinders 5, 3 and I0 andby pipes 431 to the pullback end 33 of cylinder 5 and by pipes 33 to thestripping cylinder I3. Usual valves to compensate for the differentialfluid volume to the respective cylinders during up and down operationsvof their rams are omitted for the sake of simplicity, although suchdevices are well-known in the art. When the platen Il is in itsuppermost position its arm 39 holds a rod 40 and bell crank 4I in theposition shown in Fig. 1 Whereby the usual pump control rod 42 shiftsthe pump substantially to its neutral position. To initiate the downstroke the operator manually rotates the bell crank in thecounterclockwise direction until engaged and held by alatch 43. Suchcounterclockwise movement shifts the pump forwardly to discharge fluidthrough pipe 36 to the cylinders 5, 9 and III and to draw iiuid from thepipes 31 and 38. As the plunger engages `the powdered metal in mold 2ithe pumppressure builds up in the main cylinders and when this pressurereaches a predetermined densifying value a piston 44 is moved against anadjustable spring 45'to release latch 43 whereupon a compression spring45 shifts the pump through its `stern 42 to a reversing position so asto supply fluid through pipe 31 to the diierential cylinder end 33 andalso through pipe 38 to the stripping cylinder I3 thereby. moving platenI2 downward- 1 y to eject the formed product from mold 2|. When thepress returns to near its upper position it engages nut 40' to lift. rod40 and return the pump to neutral. If desired, the press operations may4be continuously repeated without stopping by employing any welll-knownrepeating cycle control. However, for purposes of my invention in regardto the densifying operation theabove single stroke operation willsuffice.

has heretofore 50 and 5| and 'I'he dimensional control mechanisincomprises, in one speciiic form of the invention, a pair of wedge seatmembers Eiland 5I, Fig. 1, bolted or otherwise suitably secured tocrosshead I4 and which, if necessary, may be suitably shimmed asindicated at 52. Wedge blocks 53 and 54 are interposed between ytheseats the under surface of crosshead I.

The wedges 68 and 54 are each provided with non-rotatable threadedshafts 55 and 56 guided in brackets 51'and-68 and have threadedengagement with gear nuts generally indicated at 69 and 68. Tosimultaneously drive the two gear nuts, a pair of pinions 6I and 62 aresecured to a common pinion shaft 63 which is driven by a motor 64. Bymoving the wedgeblocks 53 and 54 inwardly the upper movement of platenI2 is reducedand conversely by moving the wedges outwardly the platen I2may move to a higher position. Increasing or decreasing verticalmovement of platen I2 eiects -a corresponding in-A crease or decrease ofthe volume of die 2l inasmuch as plunger 24 remains stationary. 'I 'hecooperative relation of the wedge mechanism to the crosshead I4 is suchthat the wedges may be adjusted during continuous operation of the presswithout stopping the same thereby permitting adjustment betweensuccessive products or any se- 'as a unitary part of, a support 89 whichis v'ertically adjustable by the screw 89'. The upper end of the bellowsis vsecured to a container 9| .which is biased downwardly by a spring92. A fulcrum 93 engages a wedge arm 94 pivotedcat 95 while the outerend of the arm carries a pair of resilient wedge actuating lingers 96and 91.

Operation of dimensional control-Assuming that the' control apparatus is-set for a predetermined dimension of the products 1|, when the controlcircuit is energized by the pawl and ratchet control 14, 15 and 16 thevalve 98 is raised and air pressureis supplied to jet 10. If theproduct' II has a smaller dimension than desired the clearance betweenthe top of the article and the jet orice will be larger than normal andaccordingly air pressure may flow more freely from.

the jet resulting in a corresponding drop of pressure in the jet pipe 18below normal.

ybetween the force of spring 92 and the air pres-l sure ln bellows 81and accordingly spring 92 will tainer 9I downwardly causes wedge arms 94to move downwardly about a pivot'95 thereby to I t i .permit linger 91to close a micro-switch genproduct from beneath the plungerA 30 on tothe discharge table 66 but inasmuch as such devices per se do notconstitute part of my present invention it vwill sufElce todiagrammatically indicate such a device by a dotted outline 61. Thenovel arrangement constituting the improved di- `mensional responsivemeans includes an air jet resulting from varying dimensions of theproduct, c to actuate the wedge motor 64 either forwardly or reverselyas the case may require. It is also desirable to measure say only everysixth article thereby avoiding too frequent adjustment. To energize-:thecontrol circuit in response to only 19 to wedge operating motor 64 andalso to 'at follow-up contact servo-motorA Illl. The wedge motor 64causes the wedges to be moved outwardly thereby permitting the crossheadI4 and mold platen I2 to moveto a higher position dur ing the nextoperation.v Such a higher position a selected number of articles Iprovide a pawl Y 14 pivotally-and yieldably supported on the platen vI Ifor actuating va ratchet 15 mounted on the press frame near the upperend of the platen stroke. Hence, as the platen moves upwardly' on eachstroke it will successively engage the ratchet teeth until nally anelectrical contact 16 carried and accordingly stop the first articlebeneath jet 1 18. Simultaneously a solenoid 82 is energized to open avalve 83 thereby admitting air'pressure from a suitable constantpressure source diagrammatically indicated at 84 through pipes 85 and 86-to a sylphon bellows 81. Supply pipe 84 is conof the mold platen I2increases the depth of the -mold 2| above the top of stationary plunger24 thereby to increase the axial dimension of the tating by havingslidable contact with a guide Il'l4.` When the block Il l2 has moved apredetermined distance the micro-switch |00 will move f away from linger91-and accordingly open the switch and therebydiscontinue operation ofthe motor IDI and switch operating motor 64. The press will then make,its next stroke and on its up stroke will rotate ratchet 15 sofas tobreak `engagement of contacts 16 and 11'thereby to deenergize thecontrol circuit. Upon deenergization of the control circuit the valves83 and 98 close -and solenoid 88 is deenergized to allow stop arm 8| todrop out of the panier the arucIes .thereby permitting the next seriesof articles td discharge freely from the conveyor 68. 'When the nextpredetermined number of articles, specically shown herein as six, areformed, then the pawl and ratchet 14 and 15 will again reenergizethecircuit.' Stop arm'8l will be then4 moved in front of the rst articleand the air supply will beturned on. If the articleis now of greaterheight than desired, then the clearance between the jet and article willbe reduced below normal thereby restricting the flow of air from pipe 10and accordingly cause an increase of pressure in the bellowswith'consequent raisl ing of finger 13 and closure of micro-switch |86 Iby nger. I Closure of thisswitch will reversely operate both the switchmotor 64 and the follow-up motor IUI. 'I'he wedgeswill accordingly.'

be moved inwardly to decrease the effective length of the mold cavitywhile the block |02 will be -moved upwardly until its switch is opened.The sensitivity of the apparatus as well as the normal position of thejet may be varied by an adjusting screw .|09 which raises and lowers jet10, the contact arm 94 being adjusted by screw 89. The foregoing plus orminus adjustment of the mold cavity will be repeated as often as is'necessary to maintain a uniform dimension and hence it is not necessaryto repeat further the successive measuringand adjusting operations.

To stabilize the dimensional control apparatus in between successivemeasurements of the articles, the switch arm 94 is clamped as shown inFig. 4 between a stationary back |08 and a spring A pressed piston |09.IIihis clamping action is released When valve, 98 is raised byenergization of solenoid 99 thereby supplying iluid pressure from pipe84 to a pipe I0 for moving piston |09 'outwardly against the spring Asmall amount of clearance is permitted between the I switch arm 94 andthe plate |08 and piston |09 when the clamping pressure is releasedthereby avoiding friction en the switch arm. Conversely, when valve 98is closed, then fluid pressure on piston |09 is exhausted through valve98 and pipe ||0 whereupon spring clamps switch arm 94 between piston |09and stationary back |08. To further sensitize the equipment arm 94 isprovided with a counterweight ||2 having a spring connection extendingover a pulley of an indicator pointer H3 thereby to register on a dial||4 the-extent of displacement of arm 94 from neutral.

In order to obtain dimensional control without duouo'n of powdered metalproducts. n is also seen that my improved automatic adjusting controleffectively regulates the amount of nil and that this controlisoperative to measure ilnished pieces produced by the machine. -Suchautomatic equipment may beused regardless of the character of materialused or of the type of press in which the material is compressed,although in the specific 'aspect of my invention disclosed herein ahydraulic press is adapted in combination with the densifying responsivemeans to control the density of the products in cooperation withdimensional control thereof. The diautomatic adjustment thereof, thecircuit 'I9 will be disconnected and two adjustable stop-pins H5 areplaced on `side columns 2 and 3 beneath upper platen so as to limitdownward move- -lment thereof and thereby definitely establish a fixeddimension for the product. 'I'he pins have heads and Shanksy ||6slidably received in suit-l able vertical openings found in the sidecolumns. Shims Ill may be inserted to obtain any desired dimension. Thisdimensional control may be accompanied by density control by manuallycontrolling the adjustment of the wedge stops 53 fand 54 through closingone or the other of reversingor forward switches ||8 and ||9 connectedto a suitable source of current. This current actuates motor 64 andthereby adjusts the wedges 53 cavity 2| and accordingly determine theamount of iill'and the density of the product. From this disclosure itis seen that during manual dimensional control through use of stops H5the adf justing wedges perform a density control function but duringautomatic dimensional control the wedges perform a dimensional controlfunction, the pins ||5 are removed when the auto matic dimensionalcontrol is employed. During automatic dimensional control, densitycontrol is 'obtained by controlling the hydraulic pressing fluidpressure. Also" during automatic dimensional control the switches I0 and||9 permit a preliminary dimensional -adjustment `of vwedges mensionalaccuracy of the equipment is further enhanced by the cooperative actionof the preshrunk ring 22 on the die mold -20 thereby maintaining theradial dimension of the article.

It. will of course be understood that various changes in details oiconstruction and arrangement of parts may be made by those skilled inthe art without departing from the spirit ofthe invention as set forthin the appended claims.

I claim:

1. Apparatus for Vforming products of loose material comprising, incombination, a platen having a mold, means for adjusting the effectivedepth of said mold to control the axial dimension Y includes an `air jetdirected against a product with a predetermined clearance whereby anyvproduct whose dimension causes a variation in said clearance then saidclearance will produce a corresponding change in jet pressure, and meansresponsive to the change in jet pressure from a predetermined value foradjusting the eil'ective depth of the mold.

4. Apparatus for forming products of loose material comprising, incombination, a press having a platen mold, a compressing plunger,

' and 54 so as to adjust the height of the mold ll and 54 while the airjet control effects a precision control.

From the foregoing disclosure it is seen that YI have providedl improvedpress equipment that is relatively simple and rugged combined .withpositive operationl that has a high degree of sensitivity. accuracy andV responsiveness in'the propower operated means for adjusting theeffective depth of the mold to vary the axial dimensmn of a productformed in the mold, means for measuring the axial dimension of a productdischarged from the press, and means controlled by said measuring meansfor initiating operation of said power means.

5. The combination set forth in claim 4 further characterized in thatsaid means which is responsive to the measuring means includesrelativelymovable cooperating elements which upon va predeterminedmovement of one of said elements effects said initiation of the powermeans, and means also initiated by said predetermined relative movementfor causing actuation of the other of saidA elements'until the initialrelationship between -the elements is re-established thereby todiscontinue any further dimensional adjustment of the mold.

6. The combination set forni in omini 4 mr-v ther'characterized by theprovision of means for adjusting the measuring means so ast'o establisha-predetermined dimension for the products.

7,. The combinationset forth in claim -i rurther characterized in thatsaid measuring means and dimensional adjusting means forthe mold arerendered periodically operative automatically in accordance with thenumber ofA products produced.

8. The combination set forth in claim 4 further characterized in thatsaid measuring means and said dimensional control means for the mold arecontrolled by an electrical circuit, and means actuated in accordancewith a predetermined operation of the apparatus for controlling saidcircuit and thereby initiating the measuring operation. 'v 9. Apparatusfor forming products of loose material comprising, in combination,mechanism for forming the products including a mold and a plunger, meansfor adjusting said mechanism to vary a dimension of the products, meansfor measuring said dimension of the products after they are dischargedfrom said forming mechanism, and means responsive to said measuringmeans for actuating said dimensional adjusting means when the dimensionof the product varies from a predetermined value.

A10. Apparatus for forming products yof loose material comprising, incombination, a platen having a mold, means for adjusting the effectivedepth of said mold to control the axial dimension of a product formedtherein, means for prelirninarily actuating said adjusting means tobring the effective depth of said mold within predetermined axiallimits, precision adjusting means for also actuating said adjustingmeans to vary the depth of said mold, means for measuringtheaxialdimension of a product discharged from said mold, and means forautomatically rendering said precision adjusting means operative inresponse to said measuring means'when the measurement varies from apredetermined value. Y

k11. The combination set forth in claim 10 fur-- y ther characterized bythe provision of means for JOHN B. CUTLER

